Review Reports - High Speed Roll Caster for Aluminum Alloy

Round 1

Reviewer 1 Report

Please refer to the attachment.

Comments for author File: Comments.pdf

Author Response

Dear Sir

Thank you for kind suggestion.

I have been revised according to your recommendation.

Please check the revised manuscript.

Best regards,

Toshio Haga

The basic design concept of a twin-roll caster for aluminum alloy has not changed for more than sixty years. As a result, the casting speed is still very low, and high-additive-element Al alloy cannot be cast even now as a result of the lack of cooling ability. This review paper describes the development of three types of novel high-speed roll casters for aluminum alloy proposed in our laboratory, as well as the properties of these casters and strips cast using these casters. Emphasis is placed on the development and properties of the novel high-speed roll casters.

Revised part is show by blue text in a revised manuscript.

Q1. Figure 6 shows the outer surfaces of bent strips cast using three types of casting conditions.

Will it have an impact on subsequent molding? How to eliminate it?

A1. Convex surfaces could be flattened by cold rolling, as described in the following text of the revised manuscript:

“Convex strip surfaces, shown in Figures 7(b), 7(c), and 8(b), were flattened by cold rolling.”

Q2. The flow field study has a great influence on the liquid-level fluctuation of melt and the

surface quality of product. Whether to conduct relevant research on the flow field at the

position shown in Fig. 8.

A2. In this process, liquid-level-fluctuation does not influence the surface condition because the melt pool is supported by side dam plates and back dam plates. This is different from the conventional twin-roll caster for aluminum alloy.

The vertical burr became a horizontal burr by means of the burr changer. The quantity of the vertical burr is similar to that of the horizontal burr. The semisolid metal at the mid-thickness position is squeezed to both edges of the strip and becomes a burr. In this way, the use of a burr changer did not influence the strip surface or flow field of the molten metal.

Q3. Deep Drawing Test is a relatively important research method in this paper. Please provide

the equipment used for the test and the corresponding parameters.

A3. A conventional deep drawing testing machine was used. The punch diameter and blank hold pressure are shown in the captions of the figures, and these parameters are thought to be sufficient to estimate the deep drawing condition.

Q4. The relative mechanism is not strong, it is suggested to supplement the research summary

of heat transfer law during the casting process.

A4. The effect of the melt head on the improvement of the heat transfer coefficient was added in the text of the revised manuscript, as follows:

“The effect of the melt head on the heat transfer coefficient between the molten metal (or solidification layer) and the roll was investigated using a melt-drag single-roll caster and Al-12 mass% Si. When the melt head was changed, the solidification length was kept constant by adjusting the position of the nozzle, as shown in Figure 1. The heat transfer coefficient was calculated from the strip thickness and solidification time using the one-dimensional finite differential method. The heat transfer coefficient increased as the molten melt head became higher, as shown in Figure 1. The cooling rate increased as the heat transfer coefficient increased. The higher cooling rate is useful, for example, to make fine eutectic Si and the inter metallic compound included as impurities.”

In addition, Figure 1 was revised in the new manuscript.

Q5. There are too many schematic diagrams in the paper, and some of them lack relevant

evidence. So it is necessary to add some Real diagrams which can represent the actual

situations.

A5. Photographs of the caster and casting procedure and close-up photographs near the roll and the scraper are shown in place of schematic diagrams. Moreover, the roll size, solidification length, roll load, and casting speed were added. Estimation of the positional relationship of parts is thought to become easy.

Q6. The reviewer reviewed the previous reference and believed that the proportion of self-cited reference was too high, and the content was very repetitive. Therefore, it was necessary to concentrate the views of important reference.

A6. The references have been revised according to your recommendation.

Author Response File: Author Response.pdf

Reviewer 2 Report

This publication is a review related to the evaluation of the work done over a 20-year period to study the High Speed Roll Aluminum Casting method.

In this regard, the author should add an assessment of the data obtained to determine their value for the metallurgical field, science and society. It is necessary to select only significant works for analysis, and not all of them as they are now (for example, such references as [12-77], [21-54] , etc.), and to analyze in detail the dynamics of the study of the problem of high-speed roller casting. At the end of the article, the results of the three casting methods are summarized in one table. And most importantly, describe the current state of a narrow field of knowledge with prospects for its development.

You also need to add the scale in Figures 3a, 3b, 19a, 19b.

In Figure 9a, align the horizontal centerlines.

Replace the primitive figure 19d with text and add a photo of the casting installation with a scraper, or better yet, the casting process itself.

Author Response

Dear Sir

Thank you for kind suggestion.

I have been revised according to your recommendation.

Please check the revised manuscript.

Best regards,

Toshio Haga

Revised part is show by blue text in a revised manuscript.

Q1. The author should add an assessment of the data obtained to determine their value for the metallurgical field, science and society.

A1. It is difficult to assess the obtained data in this manner. However, a) the VHSTRC is shown to be suitable for improvement of the decreased mechanical property of recycled aluminum alloy; b) Al-SiCp strip cast by the VHSTRC had good ductility, and SiC particles were uniformly dispersed without agglomeration; c) strip of A356 aluminum alloy for casting using UDTRC had fine eutectic Si and deep drawing and full bending could be conducted; and d) 5182 alloy (Al-5%Mg) strip without center segregation could be cast using the SRCs. It may be possible to assess the metallurgical properties of strips cast using high-speed twin-roll casters. The important thing is that the properties of the high-speed twin-roll casters can be estimated based on these results.

Q2. It is necessary to select only significant works for analysis, and not all of them as they are now (for example, such references as [12-77], [21-54] , etc.).

A2. The references have been revised according to your recommendation.

Q3. It is necessary to analyze in detail the dynamics of the study of the problem of high-speed roller casting.

A3. The method used to increase the casting speed (given in Section 2 “Vertical-type High-speed Twin-roll Caster”) is as follows: a) the increase in the thermal conductivity of the roll, b) the non-use of a parting material to increase the thermal conductivity, and c) the use of the hydrostatic pressure of the molten metal. The effectiveness of these techniques for increasing the casting speed is clarified in the revised paper.

Q4. At the end of the article, the results of the three casting methods are summarized in one table.

A4. Table , which compares three types of roll caster, has been added to the revised manuscript at the end of the summary.

Q5. Most importantly, describe the current state of a narrow field of knowledge with prospects for its development.

A5. Current research toward development and prospects for practical application were summarized as follows, and has been added to the revised manuscript at the summary.

“More detailed investigations of the small roll load and the pouring temperature directly over the liquidus line of the molten metal are required in order to obtain an improved surface of the strip based on recent studies on high-speed twin roll casters. Such studies have begun. A horizontal-type twin-roll caster that incorporates the ideas of the high-speed twin-roll caster has been used for strip casting of magnesium alloy. Practical application research on the VHSTRC for aluminum alloy is planned to begin from the second half of 2021 in Japan. Problems in the actual operation of the VHSTRC will be clarified by practical application research.”

Q6. Need to add the scale in Figures 3a, 3b, 19a, 19b.

A6. The figures have been revised according to your recommendation.

Q7. In Figure 9a, align the horizontal centerlines.

A7. The figure has been revised according to your recommendation.

Q8. Replace the primitive figure 19d with text and add a photo of the casting installation with a scraper, or better yet, the casting process itself.

A8. Figure 19(d) (Figure 21 in a revised paper) has been replaced with a photograph of the casting process.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

I am satisfied with the adjustment.